What calculator did you use? Libelldra? I got these.
Timid Palkia using Aqua Tail against a max HP/max Def Bold Blissey
248 Atk vs 130 Def & 714 HP (108 Base Power): 331 - 391 (46.36% - 54.76%)
Rain and Lustrous Orb took into account. 98% to 2HKO with Stealth Rock and leftovers. You also get the OHKO on Latias if you use outrage.
Timid Palkia using Aqua Tail against a max HP/max Def Bold Blissey
248 Atk vs 130 Def & 714 HP (108 Base Power): 331 - 391 (46.36% - 54.76%)
Rain and Lustrous Orb took into account. 98% to 2HKO with Stealth Rock and leftovers. You also get the OHKO on Latias if you use outrage.